A problem often encountered in the polymer film art relates to the difficulty of providing strong adhesion between substrates and functional coatings applied to them. This is particularly true for polyester-based substrates. To deal with the problem, a primer layer or coating is often applied to the polyester substrate to improve adhesion between the substrate and the functional coating.
Among the primer technologies that have been used to provide improved adhesion between polyester-based substrates and functional coatings applied to them are: the use of aminosilane coatings to improve the adhesion at subfreezing temperatures as described in U.S. Pat. No. 5,064,722 (Swofford et al.); PET (polyethylene terephthalate) films primed with polyallylamine coatings to improve adhesion to the PET film of a polyvinyl butyral or ionoplast resin layer, as described in U.S. Pat. No. 7,189,457 (Anderson); glass laminates for reduction of sound transmission that may include 3-layer laminates of polyester film positioned between two dissimilar polymer layers, as described in U.S. Pat. No. 7,297,407 (Anderson); and the primer layers for multi-layer optical films where the primer layer may include a sulfopolyester and a crosslinker, as described in PCT Publication No. WO 2009/123921.